The black-headed gull (Chroicocephalus ridibundus) is a small gull which breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population is migratory, wintering further south, but some birds in the milder westernmost areas of Europe are resident. Some birds will also spend the winter in northeastern North America, where it was formerly known as the common black-headed gull. As is the case with many gulls, it had previously been placed in the genus Larus. (From Wikipedia, the free encyclopedia)
The black-headed gull is common in Denmark and Sweden.